Summary 

The Caller ID Number under Outbound Call Preferences is what OnSIP sends out as the caller-ID when an outbound call is placed. On calls to the PSTN, only  the number is accepted by the outbound carrier. If you see the caller-ID number, you have setup caller-ID correctly.

Details 

Caller ID should be set in two (2) places in your OnSIP Administrators tab.  The reason for this is the Outbound Caller ID for the User is pushed through the PSTN gateway.  If the receiving end does a lookup for the number you entered as your outbound call preference, and there is a record for it, then it will insert the name; this is not always a given, but it's best to set it in both placed within OnSIP.  In general, the name/label is typically dropped but the number is passed through. 
 
If you intend to make calls outside the US, Caller ID is required to be configured in your account for the call to be successful. 

First, log in to the Administrators tab and navigate to the Users. Click on the name of the user whose Caller ID you'd like to modify and go to the Call Settings tab. 

Click "Edit Info" to change this user's settings. You can either have the user's phone send Caller ID (Please Note: not all phones can send caller-ID settings), or provide a custom one through our interface. For custom Caller ID, select "Custom" as the PSTN Caller ID, and fill in the name and phone number you would like to appear as Caller ID. The custom setting will then over-ride anything sent by the phone. 

When you're done, click "Save Changes". If everything went okay, you should see your settings in the Outbound Call Preferences section. Otherwise, you will be given an error message and asked to fix what went wrong. 

Second, from the Administrators tab, select Phone Numbers. Click on the phone number(s) for the Caller ID you'd like to modify.  Click "Edit Info, then under Outbound Caller ID Name you can choose to use the contact information, unspecified or custom. If you select custom, you can then enter the label (Caller ID) for this phone number and Save Changes.  

Setting Default Caller ID click here 

Can't Call Toll Free Numbers: 

If you have problems calling toll free numbers, it may be a problem with your outbound caller-ID number. Make sure that your caller-ID number is a valid 11-digit phone number and not, itself, a toll-free number. Many toll-free numbers reject calls without a valid caller-ID or if the caller-ID is a toll-free number.